Droz. I. Pierre Jacquet, a Swiss mechanician, born at La Chaux-de-Fond, July 28,1721, died at Bienne, in the canton of Bern, Nov. 28, 1790. In the divinity school of Basel he prepared for the church, but on his return home his attention became directed to the manufacture of watches and clocks, for which his native town is celebrated. He eventually perfected the different parts of clockwork, and supplied common timepieces with a musical machinery which imitated a chime of bells and the sounds of the flute. He made many experiments for the purpose of effecting perpetual motion. His most ingenious contrivance was a pendulum composed of two metals of unequal dilatability to counteract the effects of heat and cold. This was purchased by the king of Spain, who bestowed a pension upon the inventor. His most celebrated production was a writing automaton, which moved its fingers and hands, and formed letters. At the time of his death he was engaged upon the fabrication of a new astronomical clock. II. Henri Louis Jacquet, son of the preceding, born Oct. 13, 1752, died in Naples, Nov. 18, 1791. In 1774 he removed to Paris, and became celebrated for his mechanical productions, especially an automaton representing a young lady playing on the harpischord, following the music with her eyes and the movements of her hands, and, when done playing, rising and bowing to the audience.

The most famous specimen of his inventive genius in this respect was a pair of artificial hands which he devised for La Rayniere, who had lost his hands during a hunting expedition.